﻿/*
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.

Copyright (C) 2005-2014  Sylvain Rougeaux (Cyber Sinh) (http://www.luminescence-software.org/)
*/

using System;
using System.IO;
using System.Linq;

namespace Luminescence.Xiph
{
   /// <summary>
   ///   Classe immuable stockant les données d'une page Ogg.
   /// </summary>
   public class OggPage : IEquatable<OggPage>
   {
      /// <summary>
      ///   Identificateur d'une page Ogg.
      /// </summary>
      protected static readonly byte[] OggS = { 0x4F, 0x67, 0x67, 0x53 };

      /// <summary>
      /// La taille maximale en octet d'une page Ogg.
      /// </summary>
      public const int MaxPageLength = 65307;

      private static readonly uint[] crc_lookup =
         {
            0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9, 0x130476DC, 0x17C56B6B, 0x1A864DB2, 0x1E475005,
            0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61, 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD,
            0x4C11DB70, 0x48D0C6C7, 0x4593E01E, 0x4152FDA9, 0x5F15ADAC, 0x5BD4B01B, 0x569796C2, 0x52568B75,
            0x6A1936C8, 0x6ED82B7F, 0x639B0DA6, 0x675A1011, 0x791D4014, 0x7DDC5DA3, 0x709F7B7A, 0x745E66CD,
            0x9823B6E0, 0x9CE2AB57, 0x91A18D8E, 0x95609039, 0x8B27C03C, 0x8FE6DD8B, 0x82A5FB52, 0x8664E6E5,
            0xBE2B5B58, 0xBAEA46EF, 0xB7A96036, 0xB3687D81, 0xAD2F2D84, 0xA9EE3033, 0xA4AD16EA, 0xA06C0B5D,
            0xD4326D90, 0xD0F37027, 0xDDB056FE, 0xD9714B49, 0xC7361B4C, 0xC3F706FB, 0xCEB42022, 0xCA753D95,
            0xF23A8028, 0xF6FB9D9F, 0xFBB8BB46, 0xFF79A6F1, 0xE13EF6F4, 0xE5FFEB43, 0xE8BCCD9A, 0xEC7DD02D,
            0x34867077, 0x30476DC0, 0x3D044B19, 0x39C556AE, 0x278206AB, 0x23431B1C, 0x2E003DC5, 0x2AC12072,
            0x128E9DCF, 0x164F8078, 0x1B0CA6A1, 0x1FCDBB16, 0x018AEB13, 0x054BF6A4, 0x0808D07D, 0x0CC9CDCA,
            0x7897AB07, 0x7C56B6B0, 0x71159069, 0x75D48DDE, 0x6B93DDDB, 0x6F52C06C, 0x6211E6B5, 0x66D0FB02,
            0x5E9F46BF, 0x5A5E5B08, 0x571D7DD1, 0x53DC6066, 0x4D9B3063, 0x495A2DD4, 0x44190B0D, 0x40D816BA,
            0xACA5C697, 0xA864DB20, 0xA527FDF9, 0xA1E6E04E, 0xBFA1B04B, 0xBB60ADFC, 0xB6238B25, 0xB2E29692,
            0x8AAD2B2F, 0x8E6C3698, 0x832F1041, 0x87EE0DF6, 0x99A95DF3, 0x9D684044, 0x902B669D, 0x94EA7B2A,
            0xE0B41DE7, 0xE4750050, 0xE9362689, 0xEDF73B3E, 0xF3B06B3B, 0xF771768C, 0xFA325055, 0xFEF34DE2,
            0xC6BCF05F, 0xC27DEDE8, 0xCF3ECB31, 0xCBFFD686, 0xD5B88683, 0xD1799B34, 0xDC3ABDED, 0xD8FBA05A,
            0x690CE0EE, 0x6DCDFD59, 0x608EDB80, 0x644FC637, 0x7A089632, 0x7EC98B85, 0x738AAD5C, 0x774BB0EB,
            0x4F040D56, 0x4BC510E1, 0x46863638, 0x42472B8F, 0x5C007B8A, 0x58C1663D, 0x558240E4, 0x51435D53,
            0x251D3B9E, 0x21DC2629, 0x2C9F00F0, 0x285E1D47, 0x36194D42, 0x32D850F5, 0x3F9B762C, 0x3B5A6B9B,
            0x0315D626, 0x07D4CB91, 0x0A97ED48, 0x0E56F0FF, 0x1011A0FA, 0x14D0BD4D, 0x19939B94, 0x1D528623,
            0xF12F560E, 0xF5EE4BB9, 0xF8AD6D60, 0xFC6C70D7, 0xE22B20D2, 0xE6EA3D65, 0xEBA91BBC, 0xEF68060B,
            0xD727BBB6, 0xD3E6A601, 0xDEA580D8, 0xDA649D6F, 0xC423CD6A, 0xC0E2D0DD, 0xCDA1F604, 0xC960EBB3,
            0xBD3E8D7E, 0xB9FF90C9, 0xB4BCB610, 0xB07DABA7, 0xAE3AFBA2, 0xAAFBE615, 0xA7B8C0CC, 0xA379DD7B,
            0x9B3660C6, 0x9FF77D71, 0x92B45BA8, 0x9675461F, 0x8832161A, 0x8CF30BAD, 0x81B02D74, 0x857130C3,
            0x5D8A9099, 0x594B8D2E, 0x5408ABF7, 0x50C9B640, 0x4E8EE645, 0x4A4FFBF2, 0x470CDD2B, 0x43CDC09C,
            0x7B827D21, 0x7F436096, 0x7200464F, 0x76C15BF8, 0x68860BFD, 0x6C47164A, 0x61043093, 0x65C52D24,
            0x119B4BE9, 0x155A565E, 0x18197087, 0x1CD86D30, 0x029F3D35, 0x065E2082, 0x0B1D065B, 0x0FDC1BEC,
            0x3793A651, 0x3352BBE6, 0x3E119D3F, 0x3AD08088, 0x2497D08D, 0x2056CD3A, 0x2D15EBE3, 0x29D4F654,
            0xC5A92679, 0xC1683BCE, 0xCC2B1D17, 0xC8EA00A0, 0xD6AD50A5, 0xD26C4D12, 0xDF2F6BCB, 0xDBEE767C,
            0xE3A1CBC1, 0xE760D676, 0xEA23F0AF, 0xEEE2ED18, 0xF0A5BD1D, 0xF464A0AA, 0xF9278673, 0xFDE69BC4,
            0x89B8FD09, 0x8D79E0BE, 0x803AC667, 0x84FBDBD0, 0x9ABC8BD5, 0x9E7D9662, 0x933EB0BB, 0x97FFAD0C,
            0xAFB010B1, 0xAB710D06, 0xA6322BDF, 0xA2F33668, 0xBCB4666D, 0xB8757BDA, 0xB5365D03, 0xB1F740B4
         };

      #region Propriétés

      /// <summary>
      ///   Indique si la page Ogg est corrompue.
      /// </summary>
      public bool IsCorrupted
      {
         get
         {
            uint crc = Checksum;
            ComputeCRC32();
            bool corrupted = (Checksum != crc);
            Checksum = crc;
            return corrupted;
         }
      }

      /// <summary>
      ///   Indique la taille totale en octet de la page Ogg.
      /// </summary>
      public int Size => 27 + Segments.Length + Segments.Sum(segment => segment.Length);

      /// <summary>
      ///   Indique si la page Ogg termine un paquet.
      /// </summary>
      public bool IsComplete => (Segments[Segments.Length - 1].Length < 255);

      /// <summary>
      ///   Indique si la page Ogg est la dernière du flux binaire.
      /// </summary>
      public bool IsLastInLogicalBitstream => 
         HeaderType == OggHeaderType.ContinuedPaquetInLastLogicalBitstream ||
         HeaderType == OggHeaderType.FreshPaquetInLastLogicalBitstream ||
         HeaderType == OggHeaderType.StartAndEndLogicalBitstream;

      /// <summary>
      ///   Numéro de la page dans le flux binaire.
      /// </summary>
      public int PageSequenceNumber { get; protected set; }

      /// <summary>
      ///   Type de la page Ogg.
      /// </summary>
      /// <remarks>
      ///   Returne null si sa valeur n'est pas renseignée
      /// </remarks>
      public OggHeaderType? HeaderType { get; protected set; }

      /// <summary>
      ///   Absolute Granule Position.
      /// </summary>
      public long AbsoluteGranulePostion { get; protected set; }

      /// <summary>
      ///   Numéto de série du flux binaire.
      /// </summary>
      public int StreamSerialNumber { get; protected set; }

      /// <summary>
      ///   Données par segment de la page Ogg.
      /// </summary>
      protected byte[][] Segments { get; set; }

      /// <summary>
      ///   Checksum.
      /// </summary>
      [CLSCompliant(false)]
      public uint Checksum { get; protected set; }

      #endregion

      /// <summary>
      ///   Constructeur protégé de la classe OggPage.
      /// </summary>
      protected OggPage()
      {
      }

      /// <summary>
      ///   Données par segment de la page Ogg.
      /// </summary>
      /// <returns>Tableau de tableau d'octets contenant les données par segment de la page Ogg</returns>
      public byte[][] GetSegments() => (byte[][])Segments.Clone();

      /// <summary>
      ///   Données de la page Ogg.
      /// </summary>
      /// <returns>Tableau d'octets contenant les données de la page Ogg</returns>
      public byte[] GetData()
      {
         using (var ms = new MemoryStream(Size))
         {
            foreach (byte[] segment in Segments)
               ms.Write(segment, 0, segment.Length);

            return ms.ToArray(); 
         }
      }

      /// <summary>
      ///   Renumérote la page Ogg.
      /// </summary>
      /// <param name = "sequence">Numéro de la page Ogg dans un flux binaire donné</param>
      public void Renumber(int sequence)
      {
         if (sequence != PageSequenceNumber)
         {
            PageSequenceNumber = sequence;
            ComputeCRC32();
         }
      }

      /// <summary>
      ///   Données de la page Ogg sous forme d'un tableau d'octets.
      /// </summary>
      /// <returns>Tableau d'octets contenant les données de la page Ogg</returns>
      public byte[] ToArray()
      {
         using (var ms = new MemoryStream(Size))
         {
            ms.Write(OggS, 0, OggS.Length);

            var bw = new BinaryWriter(ms);
            bw.Write((byte)0);
            bw.Write((byte)HeaderType);
            bw.Write(AbsoluteGranulePostion);
            bw.Write(StreamSerialNumber);
            bw.Write(PageSequenceNumber);
            bw.Write(Checksum);
            bw.Write((byte)Segments.Length);

            foreach (byte[] segment in Segments)
               bw.Write((byte)segment.Length);

            foreach (byte[] segment in Segments)
               bw.Write(segment);

            return ms.ToArray(); 
         }
      }

      /// <summary>
      ///   Calcule le checksum de la page Ogg.
      /// </summary>
      protected void ComputeCRC32()
      {
         Checksum = 0;
         Checksum = ToArray().Aggregate<byte, uint>(0, (crc32, b) => (crc32 << 8) ^ crc_lookup[((crc32 >> 24) & 255) ^ b]);
      }

      /// <summary>
      ///   Retourne un tableau de pages Ogg généré à partir de données à y insérer.
      /// </summary>
      /// <param name = "paquet">Données à insérer dans des pages Ogg</param>
      /// <param name = "streamSerial">Numéro de série du flux binaire</param>
      /// <returns>Tableau de pages Ogg généré à partir des données envoyées</returns>
      public static OggPage[] CreateFromPaquet(byte[] paquet, int streamSerial)
      {
         if (paquet.Length % 255 == 0)
         {
            var newPaquet = new byte[paquet.Length + 1];
            paquet.CopyTo(newPaquet, 0);
            paquet = newPaquet;
         }

         byte[][] segments = paquet.Split(255);
         const int maxSegmentByPage = 32; // taille max visée pour une page : 32 * 255 = 8 KB
         var nbPage = (int)Math.Ceiling(segments.Length / (double)maxSegmentByPage);

         var pages = new OggPage[nbPage];
         int offset = 0;

         for (int i = 0; i < pages.Length; i++)
         {
            int nbSegments = segments.Length - offset;
            if (nbSegments > maxSegmentByPage)
               nbSegments = maxSegmentByPage;
            var seg = new ArraySegment<byte[]>(segments, offset, nbSegments);
            offset += seg.Count;

            int k = 0;
            var data = new byte[seg.Count][];
            for (int j = seg.Offset; j < (seg.Offset + seg.Count); j++)
            {
               data[k++] = seg.Array[j];
            }

            pages[i] = new OggPage
               {
                  StreamSerialNumber = streamSerial,
                  Segments = data,
                  HeaderType = i == 0 ? OggHeaderType.FreshPaquetInContinuedLogicalBitstream : OggHeaderType.ContinuedPaquetInContinuedLogicalBitstream
               };
         }

         return pages;
      }

      #region Membres IEquatable<OggPage>

      /// <summary>
      ///   Retourne vrai si la page Ogg est identique à la page Ogg spécifiée.
      /// </summary>
      /// <param name = "other">Page Ogg à tester</param>
      /// <returns>True si les deux pages Ogg sont identiques, sinon False</returns>
      public bool Equals(OggPage other) => (other.Checksum == Checksum);

      /// <summary>
      ///   Surcharge de l'opérateur "==".
      /// </summary>
      /// <param name = "page1">Première page Ogg</param>
      /// <param name = "page2">Seconde page Ogg</param>
      /// <returns>True si les deux pages Ogg sont identiques, sinon False</returns>
      public static bool operator ==(OggPage page1, OggPage page2) => page1.Equals(page2);

      /// <summary>
      ///   Surcharge de l'opérateur "!=".
      /// </summary>
      /// <param name = "page1">Première page Ogg</param>
      /// <param name = "page2">Seconde page Ogg</param>
      /// <returns>True si les deux pages Ogg sont différentes, sinon False</returns>
      public static bool operator !=(OggPage page1, OggPage page2) => !page1.Equals(page2);

      /// <summary>
      ///   Fonction de hachage pour la page Ogg.
      /// </summary>
      /// <returns>Code de hachage pour la page Ogg</returns>
      public override int GetHashCode() => (int)Checksum;

      /// <summary>
      ///   Retourne vrai si la page Ogg est identique à l'objet spécifié.
      /// </summary>
      /// <param name = "obj">Objet à tester</param>
      /// <returns>True si les deux objets sont identiques, sinon False</returns>
      public override bool Equals(object obj)
      {
         if (!(obj is OggPage)) return false;

         return Equals((OggPage)obj);
      }

      #endregion
   }
}